The Kummle application discloses a welding machine used in conjunction with a production line that includes a roll forming machine. The Kummle application discloses a method wherein the heads of laser welders move vertically up and down for forming welded seams along vertically varying lines for workpieces which have heights which vary along their lengths. However, vertical movements of the laser welders may not be sufficient to produce satisfactory welds because the points of maximal engagement of two parts being welded are not always in the vertical plane along which the laser welders move.
The Kummle patent discloses a welding device in line with a roll forming machine. The welding device includes a single energy source connected with at least two welding heads for simultaneously producing two weld joints on a pair of roll-formed workpieces.